An electrical simulator of moving prey for the study of feeding strategies in sharks, skates, and rays

In order to further the investigation of the electric sense in elasmobranch fish, an electronic device was developed which simulates the bioelectric fields of moving prey fish. Using primarily CMOS integrated circuitry, a digital control system switches a regulated dipole current along a linear array of electrodes, thereby producing a spatial sequence of prey-simulating fields. The instrument permits control over the position of the “prey fish,” its speed of travel (1 to 100 cm/sec), and the output-current strength (1 to 10 μA). The moving-prey simulator was designed to determine whether elasmobranches orient to the prey field and strike at their victims from a distance, or whether they approach gradually, allowing for movements of the target. Preliminary results indicate that these predators, after taking aim and initiating their attacks, refrain from further course corrections. Thus, the electrical prey simulator offers the user a valuable tool for studying the dynamics of electrical prey detection.